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Mal-descent of the testis

Section: Urology Curriculum: Curriculum, page 5

Definition

  • Cryptorchidism: A testis that is not within the scrotum and does not descend spontaneously by 4 months of age
    • May be absent or undescended

Terminology

  • Undescended testes – testes that stop short along their normal path of descent into the scrotum
  • Absent testes – due to agenesis or atrophy secondary to intrauterine vascular compromise (prenatal testicular torsion) or testicular regression syndrome
  • Retractile testes – normally descended testes that can be pulled into a suprascrotal position by the cremasteric reflex
  • Ascending testes – testes in a scrotal position in early childhood and then ‘ascend’ and become undescended – can occur at any age before puberty
  • Ectopic testes – testes that descend normally through the external ring but are then diverted to an aberrant position, i.e. outside of line of normal descent – e.g. suprapubic region, femoral canal, or perineum or contralateral scrotal compartment

Incidence

  • Most common congenital abnormality of the GU tract
  • 2-5% of full-term and 30% of premature male infants
  • Most (70%) will descend spontaneously by 1 yr
  • 1% by 1 year of age
  • 1% of adults

Risk Factors

  • Prematurity
  • SGA at birth
  • Birth weight < 2.5kg
  • Prenatal exposure to endocrine-disrupting chemicals, e.g. diethylstilbesterol, pesticides
  • Family history

Pathogenesis

  • See Gonadal embryology
    • 8-15 weeks - Transabdominal descent
      • Pulled by shortening of the Gubernaculum
        • Influenced by anti-Müllerian hormone from Sertoli cells
      • peritoneum forms a pouch, the processus vaginalis, which follows the gubernaculum
    • Inguinoscrotal descent - 25-35 weeks
      • Androgen dependent
        • Relied on testosterone from Leydig cells
      • By 35 weeks decent compelte and PV closes leaving the tunica vaginalis
  • Cause
    • Hormonal
      • anti-Müllerian hormone from Sertoli cells
      • testosterone from Leydig cells
    • Mechanical
      • Abnormalities of the Gubernaculum
      • Tight inguinal ring, adhesions
    • Environment and maternal factors
      • Prematurity
      • SGA at birth
      • Birth weight < 2.5kg
      • Prenatal exposure to endocrine-disrupting chemicals, e.g. diethylstilbesterol, pesticides
    • Genetic
      • Family history
      • Genetic mutations or syndromes (e.g., Klinefelter syndrome, Prader-Willi syndrome) linked to a higher likelihood of undescended testes.

Clinical Presentation

History

Overview

  • 10% are bilateral
    • Genetic test + karyotype
  • More common if associated with other conditions
  • In unilateral cases ⇒ Left side more common
  • Some testes fully descend in infancy and then ascend during childhood (between ages 4-8)
  • 90% of true or infantile undescended testes associated with patent processus vaginalis

Key Aspects

  • Presence of testes in scrotum in neonatal period?
    • If present, then more likely to be retractile than true undescended
  • Previous inguinal surgery?
    • May indicate iatrogenic cryptorchidism related to mechanical tethering of the testis or cord in scar tissue
  • Evidence of endocrine abnormalities during pregnancy?
  • Family history of unexplained neonatal deaths or genital anomalies, abnormal pubertal development or infertility?
    • May indicate associated genetic condition

Examination

Overview

  • Empty or hypoplastic or poorly rugated scrotum or hemiscrotum
  • Inguinal fullness
  • Most common location: just outside external ring
    • Next most common: Inguinal canal
    • Next most common: Abdomen
  • Unilateral non-palpable testis with an enlarged contralateral testis may suggest testicular absence or atrophy, esp. after the onset of puberty
  • 20% of testes non-palpable

Examination Details

  • Two hand technique
  • One hand placed near ASIS, the other on the scrotum
  • First hand fingertips sweep from ASIS along Inguinal Canal
  • True undescended or ectopic inguinal testis may slide or pop under the examiner’s fingers
  • Low ectopic or retractile testis may be felt by second hand
  • Differentiate between ectopic and retractile testis
    • Hold the testis in position within scrotum for at least 1 minute fatigues cremasteric muscle
    • Afterwards, retractile testis remains in scrotum while ectopic testis immediately springs out of scrotum
    • Retractile testis can often be felt if examined squatting
  • Associated examination areas:
    • Phallus – small phallus may be due to Disorder of Sex Development or Hypopituitarism
    • Urethral Meatus – Hypospadias associated with Disorder of Sex Development
    • Scrotum – hypoplastic or poorly rugated scrotum indicate decreased likelihood of spontaneous descent
    • Inguinal canal – may indicate inguinal hernia or inguinal lymphadenopathy

Associated Conditions

  • Abdominal Wall Defects
  • Neural Tube Defects
  • Cerebral Palsy
  • Disorders of Sex Development
  • Genetic Disorders causing diminished testosterone secretion, e.g. Klinefelter, Prader-Willi
  • Genetic Disorders associated with primary hypogonadism and increased gonadotropin levels, e.g. Noonan syndrome
  • Genetic Disorders that do not affect gonadotropins or testosterone, e.g. Trisomy 18, Trisomy 13

Investigation

  • USS may be useful
    • For bilateral intra-abdominal testes
  • Karyotyping and hormonal studies to determine presence/absence of testicular tissue. If absence confirmed, then no lap exploration required

Management

  • Ideally operate before 1 year of age
    • Most undescended testes at birth will descend within 4 months
    • If undescended by 4 months, unlikely to descend and will require surgery
  • Orchidopexy for palpable testes
    • Inguinal/scrotal incision
    • Gubernaculum divided
    • Cord freed at internal ring and separated from sac/ adventitial bands (lengthens cord)
    • Subcut pocket formed between skin and dartos
    • Pexy
  • If intraabdominal
    • Laparoscopic exploration to identify absent testes
    • Fowler-Stephens Procedure – Ligate testicular vessels and rely on vascular supply from arteries to vas and spermatic fascia
    • Autotransplantation (microvascular transfer)
  • Exploratory surgery
    • GA, palpate groin, if negative then open groin exploration, then laparoscopy if negative
    • Other option is Laparoscopic exploration for absent testis, if blind ending testicular vessels then confirm absent testis, if vessels and vas exit deep ring then groin exploration, if intra-abdominal testis present then can plan definitive surgery
  • If testes atrophic then orchidectomy

Prognosis

  • Reduced fertility if not in scrotum
  • 30 x increased risk of malignancy
    • Orchidopexy does not alter risk of malignancy
    • Also increased risk of malignancy in unaffected testis
  • Complications:
    • Testicular atrophy
    • Reduced fertility despite orchidopexy
    • Hernia (20%)
    • Torsion (2%)
    • Increased risk of testicular trauma
    • Malignant transformation

Follow-up

  • OPC 6/12 to confirm survival of testis and document size and location
  • Teach boys monthly self-examination and low threshold for USS if concerns

Graph View

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